rx_mongodb_lab.ts

import * as http from 'http';
import { MongoClient, Db, Collection } from 'mongodb';
import { Observable, Observer } from 'rxjs';


const URI = '';


const getDb = (uri: string) => {
    console.log('Connect!!!!');
    let connect = Observable.bindNodeCallback<Db>(MongoClient.connect);
    return connect(uri);
};


let mdb: Db;
const connect = (uri: string) => {
    if (mdb) {
        console.time('cache connect!');
        let obs = Observable.create(observer => { observer.next(mdb); });
        console.timeEnd('cache connect!');
        return obs;
    }

    console.time('create connect!');
    let obs = Observable.create(observer => {
        MongoClient.connect(uri, (err, db) => {
            if (err) return observer.error(err);
            mdb = db;
            return observer.next(db);
        });
    }) as Observable<Db>;
    console.timeEnd('create connect!');
    return obs;
};


let collll: Collection;
const createCollection = (database: Observable<Db>, collectionName: string) => {
    /*
    if (collll) {
        console.time('Cache Collection!!!!');
        let obs = Observable.create(observer => { observer.next(collll); });
        console.timeEnd('Cache Collection!!!!');
        return obs;
    }
    */


    console.time('Create Collection!!!!');
    let obs = database.flatMap(db => {
        return Observable.create((observer: Observer<Collection>) => {
            let col = db.collection(collectionName);
            collll = col;
            observer.next(col);
        }) as Observable<Collection>;
    });
    console.timeEnd('Create Collection!!!!');
    return obs;
};



const server = http.createServer((req, res) => {
    console.log('before');
    const db = connect(URI);
    const user = createCollection(db, 'user');
    user.subscribe(async function (col) {
        let username = 'fuck123';
        let result = await col.insertOne({ username });
        console.log("insert!");
        console.log(result.result.ok);
    });
    user.subscribe(async function (col) {
        let username = 'fuck123';
        let result = await col.findOne({ username });
        console.log("findone!");
        console.log(result);
    });
    console.log('after');
});
server.listen(3000);